Diskettes such as illustrated in U.S. Pat. No. 3,668,658 (Flores et al.) are in widespread use, being both inexpensive and convenient to use. Before diskettes were known, a number of patents had issued concerning magnetic recording discs which consisted of a flexible magnetic recording sheet stretched across a rigid disc-shaped support to provide a drumhead-like recording medium. While the recording disc of a diskette has a plastic film backing which inevitably experiences dimensional changes with changes in temperature and humidity, the recording area of a drumhead-like recording medium has substantially the same dimensional stability as the support, and thus can have much improved dimensional stability as compared to the recording disc of a diskette. Furthermore, a recording head may press against a stretched recording sheet without a pressure pad as is required for a diskette. A pressure pad limits the rotational speed and hence reduces access times and is also a source of wear. In spite of these advantages, such drumhead-like media apparently have not been commercially successful. Cost considerations may have inhibited their commercialization.
Drumhead-like magnetic recording media are shown in U.S. Pat. Nos. 2,662,804 (Hutton); 3,130,110 (Schmidt); 3,336,583 (Comstock); 3,373,413 (Treseder); 3,488,646 (Sugaya); 3,509,274 (Kihara); 3,537,083 (Voth); 3,599,226 (Lips); and German Offenlegungsschrift No. 2,342,890 (Boissevain). Of these, Treseder and Boissevain may provide the most complete disclosure, although neither shows how to drive its recording medium. In FIG. 1 of Boissevain, a thin magnetic recording sheet is supported in tension about an upstanding rim of a support base by a tensioning hoop. Although supported only at the rim, Boissevain suggests that the recording sheet could also be supported by a hub in the center. Since no details are given concerning the construction of either the support base or the tensioning hoop or how the product is assembled, one cannot estimate the manufacturing cost, but it probably would substantially exceed that of a diskette. The recording medium of Treseder may have a lower manufacturing cost, but mechanism to drive it rotatably would probably increase the overall costs well above those of a diskette system.
European patent application No. 80107017.8, filed Nov. 14, 1980, which is based on U.S. patent application Ser. No. 102,161 filed Dec. 10, 1979, also shows a drumhead-like recording medium wherein the recording sheet has a metal foil backing. Assembly as illustrated in FIG. 4 would be exceedingly expensive.